Since the introduction of oral contraceptives (OCs) over a quarter-century ago, research has been directed toward developing preparations that minimize the potential for side effects while maintaining efficacy and normal menstrual patterns.
During the first three to four months oral contraceptive use, the incidence rate of breakthrough bleeding and spotting rates in the first cycle are about two times higher than the rate that remains generally steady after cycle 4. This is due to the change in endometrial histology over several months of OC use that is due to a progestin effect from an OC. Several months of OC use produces a more secretory endometrium which is less prone to breakthrough bleeding. Breakthrough bleeding and spotting are the most common complaint by women first using OCs and is a common reason for discontinuing use of OCs. Breakthrough bleeding and spotting rates are higher with OCs containing amounts of estrogen less than about 30 ug, particularly in the first several months of use.
Using a constant dose of progestin, Endrikat et al., 1997 found that the break through bleeding/spotting rate for 30 ug ethinyl estradiol (EE) OC as compared to 20 ug EE OC was 68% in cycle 1, 85% in cycle 2 and 67% in cycle 3. Similarly, Akerlund et al. (1993) found that the BTB/S rate for 30 ug EE OC as compared to 20 ug EE OC was 77% in cycle 1, 60% in cycle 2 and 67% in cycle 3. These results are consistent with the conversion to a secretory endometrium occuring more quickly with an OC containing higher EE doses.
The present invention provides a contraceptive kit which helps to overcome or ameliorate the problem of breakthrough bleeding and spotting associated with lowest dose (15-20 ug EE) estrogen contraceptives.